Engine



(No Model.)

J'. SMITH. ENGINE.

No. 487,132. Patented Nov. 29, 1892.

e/y'z ATTORNEYS.

NITED STATES PATENT OFFICE.

JAMES SMITH, OF DRESDEN, NEWV YORK.

ENGINE.

SPECIFICATION forming part of Letters Patent No. 487,132, dated November 29, 1892. Application filed October 17, 1891. Serial N 0. 09,020. (No model.)

'To all whom it may concern.-

Be it known that I, JAMES SMITH, of Dresden, in the county of Yates and State of New York, have invented new and useful Improvements in Engines, of which the following is a full, clear, and exact description.

The object of the invention is to provide certain new and useful improvements in engines, whereby the motive agent is utilized to the fullest advantage, its pressure never falling much below exhaust-pressure after expansion has taken place.

The invention consists in certain parts and details and combinations of the same, as will be fully described hereinafter, and then pointed out in the claim.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar letters of reference indicate corresponding parts in all the figures.

Figure 1 is a sectional side elevation of the improvement. Fig. 2 is an indicator-diagram of an ordinary engine, and Fig. 3 is an indi cator-diagram of my improved engine.

The improvement consists principally in a device, preferably a valve, for connecting the two ends of a cylinder with each other at a time when the pressure of the live motive agent on the driving side of the piston is about equal to the exhaust or reservoir pressure on the other side of the piston, the pressure of the exhaust being the active force to actuate the device (to open the valve) to establish communication between the two ends of the cylinder, so as to permit the exhaust to pass to the driving side of the piston to mingle with and to reinforce the live motive agent, so that its tension is equal to the exhaustpressure up to the end of the stroke of the piston.

As shown in the accompanying drawings, the device is applied to the cylinder of an ordinary single steam-engine; but it is evident that the improvement can be readily adapted to all kinds of engines.

As shown in Fig. 1, the cylinder A contains the piston B, in which is formed alongitudinal passage 0, adapted to connect the two ends of the cylinder A with each other. At the ends of this passage 0, on the face of the piston B, are formed valve-seats adapted to receive the valves D and E, attached to a common valve-stem F, extending through the passage 0. In the passage U is arranged a coiled spring G, normally resting with its ends on the forked cross-rods G G extending transversely through the passage-way, as is plainly shown in the drawings. The ends of the spring G are adapted to be engaged by shoulders Dand E, formed on the auxiliary valve-stems D and E respectively, of the valves D and E, respectively. When no excess of pressure is on either side of the piston the valves D and E are held off their seats by the spring G, which opens outward at both ends up to the cross-rods G and G and by engaging the shoulders D and E of the auxiliary valve-stems l) and E hold the valves D and E off their seats. The spring G is of sufficient strength to hold both valves off their seats, as described, during the passage of vibrating currents and until compression or live steam seats themthat is, when a preponderance of pressure is on either side of piston, then the respective valve on that side is seated on the seat at the respective end of the passage 0, while the other valve is correspondingly moved farther off its seat, as will be readily understood by reference to the drawings, which show the valve in this position. When the valves are both unseated, they then permit the remaining portion of the exhaust agent on the exhaust side of piston to pass into the pressure side. Now when the motive agent passes into the left end of the cylinder A to drive the piston Bin the direction of the arrow a, then the motive agent seats the valve D, and communication between the two ends of the cylinder A is out off. WVhen the slide valve has cut off the supply of the motive agent, the latter expands until the pressure of the motive agent reaches a pressure corresponding to the exhaust on the opposite side of the piston B and the righthand end of the cylinder A. When the two pressures on the opposite sides of the piston B are about equal, then the valveD is opened by the force of the exhaust, so that the latter can pass through the now open passage 0 into the left-hand end of the cylinderAto mingle with the motive agent contained therein. The motive agent on the driving side is thus reinforced and prevented from falling below back or exhaust reservoir pressure up to the end of the stroke of the piston B, On the return stroke of the piston the live motive agent passing into the right-hand end of the cylinder A forces the valve E to its seat on the passage 0, so that communication between the two ends of the cylinder is cut off. The motive agent acts with supply-p ressure on the piston 13 until the supply is finally cut off and the motive agent expands until its pressure becomes finally equal to the pressure of the exhaust on the left-hand side of thepiston B, when the valve E is again opened by the force of the exhaust pressing on the said valve E from the inside of the passage 0. The eX- haust now mingles with the motive agent in the right-hand end of the cylinder A, and thus reinforces the same to prevent its pressure from falling much below exhaust or back pressure. By reference to Fig. 2 it will be seen that the pressure in the cylinder falls below back-pressure before the piston is at the end of the stroke causing the usual backpressure. As will be seen by my indicatordiagram shown in Fig. 3, the pressure does not fall below back-pressure during any time of the stroke.

It will be seen from the foregoing that the device is actuated onlyat a certain timethat is, according to the pressures at both ends of the cylinders.

I am aware that devices have been constructed to establish a communication between the two ends of the cylinder at the time the piston reaches a predetermined position, so that the device is always actuated at the same point in the travel of the piston. My device is actuated only when the live motive agent and the exhaust are in the condition above described. Thus the device is actuated at difierent times in the travel of the piston when the pressures of the motive agent or the load vary. 0

Having thus described my invention, I claim as new and desire to secure by Letters Patent In an engine, a cylinder, a piston operating therein and provided with a passage-Way and bars near the ends of the said passage-way, a spring held in the said passage-Way between the bars, and two valves held on the ends of the said passage-way and connected with each other by avalve-stem,the valve being adapted to be closed by compression and the live motive agent, and are arranged to be held off their seats by the said spring at'the time the pressures on the two sides of the piston are about equal, substantially as described.

JAMES SMITH.

Witnesses:

SETH YOUNG, J AMES F. REYNOLDS. 

